docs: def rel_line_to(self, dx, dy):
          """ Relative-coordinate version of :meth:`line_to`.
          Adds a line to the path from the current point
          to a point that is offset from the current point
          by ``(dx, dy)`` in user space.
          After this call the current point will be offset by ``(dx, dy)``.
  
          Given a current point of ``(x, y)``,
          ``context.rel_line_to(dx, dy)`` is logically equivalent to
          ``context.line_to(x + dx, y + dy)``.
  
          :param dx: The X offset to the end of the new line.
          :param dy: The Y offset to the end of the new line.
          :type float: dx
          :type float: dy
          :raises:
              :exc:`CairoError` if there is no current point.
              Doing so will cause leave the context in an error state.
  
          """
          cairo.cairo_rel_line_to(self._pointer, dx, dy)
          self._check_status()